Liquid stored erythrocytes: agglomeration, morphology, sialic acid, and toluidine blue uptake studies.

Increased tendency to reversible agglomeration in erythrocytes in outdated units has been previously demonstrated. This phenomenon occurred while post transfusion viability was still acceptable. In the present study erythrocytes of units with early agglomeration were investigated and compared with those with late agglomeration. There was no morphological characterization of these erythrocytes and their sialic acid content and the toluidine blue uptake were not lower than in late agglomeration. Thus, it seems that agglomeration reflects membranal changes, but is not directly related to the sialic acid content of the membrane or to its toluidine blue uptake.